Conventional electrical plugs are undesirable because they typically include a housing which protrudes a substantial distance from the wall once the plug is inserted into the outlet. This protrusion makes the plug susceptible to unintentional disengagement by moving objects and also prevents furniture and other objects from being placed close to the wall.
Over the years a variety of plugs have been developed which have low profile housings (hereinafter referred to as "low profile plugs"). Low profile plugs are advantageous because they have a reduced housing profile in comparison to conventional electrical plugs. As such, they are less susceptible to unintentional disengagement and permit objects to be placed closer to the wall than is possible with conventional plugs.
In most low profile plugs, the power cord exits the plug perpendicular to the prongs so as to decrease the profile of plug's housing. Hence, when the plug is inserted into a wall outlet, the power cord exits the plug housing parallel to the face of the wall outlet. These plugs are undesirable because it is possible for the cord to block other receptacles in the outlet, thereby preventing additional plugs from being inserted into the outlet. This is even more of a problem with polarized plugs or plugs incorporating a ground prong since these plugs can only be inserted into the wall outlet in one orientation.
In recognition of this problem, it is known to orient the electrical cord to ensure that it does not overlay the other receptacles in the outlet. Examples of such designs are illustrated in U.S. Pat. No. 4,927,376 issued to Dickie and U.S. Pat. No. 3,975,075 issued to Mason. Dickie discloses a low profile plug in which the cord exits the plug body at an acute angle with respect to a vertical axis of the plug. The cord then passes through a sleeve that reorients the cord with the vertical axis. Similarly, Mason discloses a profile plug in which the cord exits tangentially from a circular plug housing at such an angle that it does not overlay the other receptacles in a standard wall outlet. When several plugs are inserted into a single wall outlet, such plug designs are undesirable because all of the cords leave the outlet in the same direction. As such it is difficult to route electrical cords in several directions from a single wall outlet without entangling the various cords. Besides being unsightly, tangled electrical cords should be avoided because they can be dangerous.
This problem can be addressed by a plug design in which the cord rotates with respect to the prongs. An example of a rotatable plug is illustrated in U.S. Pat. No. 4,026,618 to Straka. However, the rotatable plug described in Straka is undesirable for several reasons. First, it is now common for electrical plugs to include three prongs. However, Straka only discloses a two-prong rotatable plug and does not provide a method for incorporating three prongs in a rotatable plug. Second, in Straka a bolt extends through the plug components to hold the components together and to serve as an axis of rotation for the plug's components. This bolt is problematic because it extends beyond the back face of the plug and hence can prevent the plug from being fully inserted into an outlet. In addition, the bolt can be loosened by rotation of the plug components. Finally, in many applications it is desirable to fix the cord's position once the plug is inserted in an outlet; however, Straka does not provide a method for quickly locking the position of the cord with respect to the prongs.
The present invention is directed to overcoming one or more of the above-noted problems.
More specifically, it is an object of the present invention to provide a low profile plug that is economical and simple to manufacture.
It is another object of the present invention to provide a low profile electrical plug in which the cord rotates 360.degree. with respect to the prongs.
Still another object of the present invention is to provide a rotatable low profile electrical plug in which the position of the cord is releasably lockable with respect to the position of the prongs.
It is another object of the present invention to provide a low profile electrical plug which can incorporate two electrical prongs or three electrical prongs without substantial design changes or manufacturing set up changes.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and appended claims, and upon reference to the accompanying drawings.